Dec. 6, 2007 -- An experimental depression treatment involving magnetic stimulation of the brain proved to be more effective than sham therapy in a large study.

Transcranial magnetic stimulation (TMS) has not been approved by the FDA for the treatment of depression. Early this year, an advisory panel for the agency found TMS to be safe, but panel members also expressed doubts about the research showing the treatment to be effective.

The newly published study, funded by the company that makes the device used to deliver the therapy, included 301 patients with major depression who had failed to respond to antidepressant drugs.

Half the patients received TMS, given five times a week in 35-minute sessions for four to six weeks. The other half received the sham therapy, but neither the patients nor those administering the therapy knew which treatment was being given.

Depression Scores Lower

Writing in the December issue of the journal Biological Psychiatry, researchers reported that response and remission rates among patients who got active TMS were roughly twice those of patients who got the sham therapy.

Butresearcher John P. O'Reardon, MD, concedes that response and remission rates were relatively low for both treatment groups. He says this is because the study included only patients who had proven resistant to previous treatments.

Between 14% and 17% of patients on the active treatment had achieved a remission after six weeks, compared with 5% to 8% of patients in the sham treatment group.

"In a less-resistant population we would expect to see higher responses," O'Reardon tells WebMD.

How TMS Works

TMS is a noninvasive procedure administered in an outpatient setting; it requires no anesthesia. During treatment sessions that last from 30 to 45 minutes, patients recline in a special chair while a specially placed coil device creates a magnetic field from the outside the body. The magnetic field induces an electric current to regions of the brain thought to regulate mood.

Treatments are typically given five times a week. O'Reardon says patients usually need a minimum of 10 sessions and as many as 30 to see improvement.

"This is a very safe treatment," O'Reardon says. "That is the major advantage. The disadvantage is the time-intensity of the treatment."

When the FDA advisory panel met in January of this year to consider TMS, officials with the agency questioned the research showing TMS to be a useful treatment for major depression.

Mayo Clinic professor of psychiatry and pharmacology Elliott Richelson, MD, who was not involved with the study, tells WebMD that he disagrees with the panel's assertion that the studies have not been convincing.

"Given that the studies involved patients who had not responded to other treatments, I think the responses they got were good," he says.

Many Patients Could Benefit

Only a few centers around the country offer TMS as a treatment for depression, but Richelson says FDA approval could change that.

He adds that the treatment could potentially benefit a wide range of patients, not just those with major depression who have failed other therapies.

"There are many patients who, for one reason or another, either can't take antidepressant medications or don't want to take them," he says. "This would be an option for them."